Lots of football players get concussions. That's how it works. It's a violent sport, and they play it for so long, that most every football player you encounter, even long-retired dads, will say, oh, yeah, I had a concussion or two. So football players not only get concussions, but they know concussions. They know the difference between a bad hit and the real thing. Surely Calvin Johnson does. Here's the Detroit Free Press:

Johnson was asked after practice today whether he had suffered one in Sept. 30 games at Ford Field.

But the Detroit Lions think something else. And they have medical professionals:

But coach Jim Schwartz said today there was nothing wrong with the concussion test that allowed Johnson to re-enter the game.

"Our evaluation was that he was not concussed," Schwartz said. "He was thoroughly checked. We're very strong in our evaluation. He was cleared to go back in the game, and he was on a protocol after that, and he was cleared then. We're very strong in our evaluation, and we are, as an organization, I think we have some credibility when it comes to concussions."

The lesson here isn't that NFL teams are mean, oppressive chronic ass-coverers, though they might be. The lesson is, rather, that all this stuff encompasses so many shades of gray that it's hard to apply an up-and-down protocol (where everyone wants the answer to be "up") to it. Alas, that's all we've got now.